Articficial arm and hand



June 30, 1942.

W. T. CARNES ARTIFICIAL ARM AND HAND Filed Aug. 1, 1940 3 Sheets-Sheet l k -m m. m

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ARTIFICIAL ARM AND HAND Filed Aug. 1, 1940 3 Sheets-Sheet 5 3nnentor Garnas'.

Patented June 30, 1942 UNITED STATES PATENT OFFICE azs'mai ARTIFICIAL ARM AND HAND William T. Carries, Kansas City, Mo.

Application August 1, 1940, Serial No. 349,375

Claims.

This invention relates to artificial arms and hands and has for one of its objects to produce a palm with articulated fingers, the fingers being opened, by means of a pull cord orfiexible connection secured to a shoulder harness, against the power of a spring in the palm which normally holds the fingers in closed position. The connection is of such character that the fingers are locked against opening except when manual force is applied through the flexible operating member extending from the shoulder harness.

With a hand mechanism of this type the wearer is always conscious of the normal position of the hand, namely, closed, and it is no longer necessary for him to note the position of the shoulder harness or to feel or visually inspect the artificial hand to determine the position of the fingers. In other words, with the hand of the invention the fingers will always be closed except when the operator is exerting a physical'effort to hold them open.

A further object of the invention is to produce compensating mechanism whereby the increased tension of the spring, as thefingers open, does not increase the amount of force which the operator must exert against the spring.

' Another object of the invention is to provide a construction in which a single flexible connection or cord functions to effect the raising of the forearm with or without the rotation of the wrist and hand, and whereby the wrist if locked against rotation can be automatically unlocked.

A still further object is to produce mechanism of simple, strong, compact and eflicient construction connecting the forearm and wrist elements,

whereby with a single pull cord the forearm can be swung upon the elbow joint in one direction and at the same time cause back and forth tuming action of the wrist and hand. or the forearm can be swung back and forth on the elbow joint without effecting any turning movement of the wrist and hand.

Another object is to provide simple spring-actuated means for interlocking the wrist to the forearm, and means actuated by a single pull cord, for breaking the interlocked relation of the wrist and forearm. to permit rotation of the wrist upon the forearm.

With the objects named in view and others as will hereinafter appear, the invention consists in certain new and useful features of construction and combinations of parts as hereinafter described and claimed; and in order that it may be fullyfunderstood, reference is to be had to the following drawings, in which:

Figure 1 is an elevational view of an artificial arm embodying the invention, the view showin the grist turned to expose the thumb side of the Figure 2 is an enlarged view looking into the hand from the back side thereof, the view also showing the adjacent portion of the hand and wrist in section.

Figure 3 is an enlarged fragmentary view of parts of the upper arm and forearm, the latter being dotted in normal or straightened condition and being shown in full lines swung upwardly upon the elbow joint.

Figure 4 is an enlarged sectional view, disclosing the mechanism for opening the fingers.

Figure 5 is an enlarged view looking into the circular wrist frame from the hand side thereof, to disclose the cooperative relation between certain clutch mechanism and the arrangement of the cord utilized in effecting elbow and wrist action, a perforated locking disk utilized to lock the wrist against rotation, being omitted.

Figure 6 is a section on the line VI-VI of Figure 5, with the perforated disk in place and also shows part of the wrist shell and part of the forearm shell.

Figure 'l is a section on the line VII-VII of Figure 5. with the clutch mechanism declutched and a locking pin advanced'to locking position.

Figure 8 is a section on the line VIII--VlI[ of Figure 6.

Figure 9 is a face view of a rock lever for effecting unclutching operation of the clutch elements of the circular frame.

Figure 10 is a. side view of the rock lever.

Figure 11 is a face view of the pulley or spool member of the clutch mechanism.

Figure 12 is a similar view of the other clutch.

member.

Figure 13 is a perspective view of the locking pin for engaging the perforated disk of the wrist mechanis Referring now to the drawings in detail, I, 2, 3, and 4 identify the upper arm, the forearm, the wrist and hand of an artificial arm for amputations above the'elbow. Body or shoulder harness is employed to support the artificial arm in place and to apply force to effect elbow, wrist and hand-opening operations through the pull applied on certain cords, as will hereinafter appear. The harness, since it forms no part of the present invention, is undisclosed as the construction and operation thereof, will be apparent by reference to that shown in my Patent No. 1,046,- 967, issued December 12, 1912.

The forearm shell is connected by elbow pivot 5 to the upper arm shell. A wrist frame 6 of circular form is rigidly secured to the lower end of The wrist shell is the forearm (Figure 2). screwed on a threaded member of a clutch mechanism, which member is rotatably mounted on said frame as hereinafter explained, and the frame has equipment hereinafter described for locking the wrist shell against rotation. There is also means for holding the hand in alignment with the forearm or at different angles thereto, forming no part of this invention and neither shown nor described herein, but disclosed in my aforesaid patent. The hand element is pivoted at I to the wrist shell, the pivot normally standing transversely to the elbow pivot, and the hand turns or swivels, with corresponding action of the wrist shell. The fingers 8 of the hand are caused to open upon the pull of a finger cord 9, and to close under the power of a retractile spring Ill located within the palm of the hand. The thumb is pivoted on and held in closed position for cooperative gripping action with the closed fingers, by a spring ll connected to the thumb, the thumb being adapted to yield and withdraw from the fingers under pressure exerted in the event anything should occur making it impossible to readily effect opening action of the fingers to release anything then being grasped. The thumb is yieldingly held as shown close to the fingers by the spring II, by an opposing relatively weak spring mechanism, not shown, as disclosed in my Patent No. 999,484. This permits the thumb to be brought to a position substantially parallel with the opened fingers, to enable a glove to be drawn over the hand. The detail construction of the thumb mechanism referred to forms no part of the instant invention.

Referring first to the finger construction and the control mechanism thereof, I2 is a shaft within and extending transversely across the palm adjacent the base of the fingers, and said shaft has a series of crank arms l3 linked to the fingers to effect their opening and closing movements as shown and described in my Patent No. 1,046,966, to which reference is herewith made. The crank shaft has a worm wheel segment H in mesh with a worm wheel I5 having tubular trunnion l6 disposed at right angles to shaft I2 and journaled on a stationary shaft I6a, secured to the plates l1 and I8, rigidly secured within the palm shell. A shaft [9, paralleling shaft lia, is mounted in said plates l1 and I8, and a tubu lar shaft |9a journaled on shaft I9 is equipped at its opposite end with an arm 20, and a peripherally grooved quadrant 2|, the arm being connected by the strong retractile spring ID, to the palm shell adjacent the base of the fingers (Figure 2). The worm wheel I5 has a diagonal passage 23 and is recessed at itsopposite sides at 24 around the ends of said passage. The finger cord 3 extends into the palm through a slot 26 in the base of the hand shell where pivoted to the wrist shell, and then extends to and around one of the tubular trunnions, and through the diagonal passage 23 of the worm wheel,'and from the latter against theother trunnion and to and around the peripheral groove of the quadrant 2|, and at its extremity is suitably anchored to the latter. The recessing of the sides oi. the worm wheel as at 24, is to accommodate the cord by minimizing the defiection thereof -in its passage to and through the wheel, and to guard against slippage of the cord (Figure 6), and is pivoted on ears 34.

relative to the wheel, a screw 21, is secured in the wheel through the cord.

With the arrangement shown and described, it will be apparent that a pull on the cord 3 applied from a shoulder harness, turns the worm wheel and hence the quadrant 2|, and thereby rocks shaft l2, against the resistance of spring I0, and opens the hand by straightening or extending the fingers, the latter returning to normal closed position under the retractive force of spring I0, immediately the preponderating force applied through the cord is relaxed. In this connection it will be noticed that the thumb is pivoted at 28 to the thumb stub 29, and has, within the palm, an arm or crank 30, connected to the retractile spring secured at its opposite end to the palm shell in any suitable manner. This spring permits the thumb to be pressed away from the closed fingers, as for example, should the finger opening cord break, so that any object then in the grasp of the hand can be released.

Referring now to the wrist mechanism, the circular frame 6 has an integral closure section 3| from which projects toward the hand, a tubular and partially threaded stem 32, providing an unobstructed passage through which the finger cord 9 extends. At opposite sides of and spaced from the stem 32, lugs 34 project from the section 3|. A clutch member sleeve 35 is journaled on the smooth surface of stem 32, and provided at its opposite end from section 3|, with an enlargement providing an outstanding wall 36 having peripheral notches, and a circular extension or flange 38, concentrically surrounding but spaced from the threaded end of stem 32, the flange 38, being externally threaded, said member 35 being rotatable only in conjunction with the wrist and hand, as hereinafter appears.

A nut 39 engaging the threaded end of stem 32 abuts the wall 36 and guards against endwise movement of the sleeve member 35, away from section 3| of the frame. The other clutch member, comprises a pulley or spool 40 journaled and slidable on sleeve member 35, and equipped with a pair of peripheral ears 4| for interlocking engagement with notches 31 of the sleeve clutch member. A light or weak spring 42 encircles the sleeve 35 and bears against the section 3|, and the pulley or spool member 40, and tends to urge and hold the latter against the tall 36 of clutch member 35. A circular yoke lever 42aloosely encircles the sleeve member 35 and spring 42 It has, at one end, a recumbent T-head 43, one arm of the head depending into the groove of the pulley or spool member, and the other arm upstanding therefrom. The opposite end of the yoke lever 42a is connected by a retractile spring 44 to an arm 45 of the frame, the spring tending to cause the lever to overpower spring 42 and withdraw the pulley or spool member from interlocking connection with the sleeve clutch member 35. The lever also has an arm 46 adapted to limit rotative movement of clutch member 35 in one direction, by intercepting the path of rotation of a clutch ear 4|, the reverse rotation being limited by the other ear 4| abutting the frame arm 43a. Obviously the use of the two spaced notches and two correspondingly spaced ears 4| is desirable chiefly for the purposes of strength, but incidentally they serve concurrently in limiting wrist-turning movements to about a third revolution.

The yoke lever 42a also has an arm 46 adapted to limit rotative movement of clutch member,

which thus can turn only with the clutch member 85. i

The forearm shell is open at its pivoted end, and in line with said open end, the upper arm shell, shown as closed at its front end but bored and slotted to accommodate certain guide sheaves presently identified, for the cord, and recessed to accommodate certain of said sheaves and a bracket for the sheaves last referred to.

A stationary cross shaft in the upper arm is disposed eccentrically of pivot 5, and forms a journal for two sheaves 52 and 53, and a hinge pintle for the bracket 54. Of the sheaves mentioned, the forearm has a sheave 55, and the upper arm shell sheaves 56 and 51. A cord 58 for effecting elbow operation of the forearm and for, at times, rotative action of the wrist and hand, extends from the harness, into the upper arm shell from the back wall thereof, and over the sheaves'56 and 51, and under sheave 55, extending thence over a sheave 58a and around the lower half of the clutch pulley or spool member, thence over a second sheave 59 mounted in the frame andthence to bracket 54 to which it is anchored. The function of the cord 58 is to effect raising movement of the forearm on the elbow joint pivot, and, under certain conditions hereinafter explained, incidentally turn or swivel the wrist and hand. If desired the forearm can be raised without effecting swivel movement of v the wrist and hand, as will hereinafter appear.

Another cord 60 extends under sheave 52 and through the upper front side of the upper arm shelland over a sheave 6| to the harness, the

, front end of said cord being secured to a springactuated dog 62 pivoted within the circular frame and adapted to prevent spring 44 from effecting disengagement of the clutch members.

A pull exerted by the harness through the cord 88 will trip the dog 52 and permit the yoke lever 42a, under'the retractile force of spring 44 to withdraw the slidable clutch pulley or spool member, from engagement with the sleeve clutch member 35. Under this condition of the parts, the raising of the forearm will merely result in the cord turning the pulley or spool member freely on the sleeve member 35 until ear 4| abuts arm 45, and without effecting turning of the wrist and hand. When the arm is lowered the cord reverses the rotation of the pulley or spool member until the other ear 4| in the present showing, abuts the frame arm 4911 as the forearm attains its normal alined relation relative to the upper arm. The cord 9, extending from the worm wheel and through passage 33, passes under sheave 53 into the upper arm and thence over sheave 53 to the harness through a slot in the front wall of the upper arm shell I (Figure 3). i

. Operation Under normal conditions, that is when the arm is pendent, the wrist is unlocked from the foreis engaged with the yoke lever 42a and preventing spring 44 from causing the latter to disengage the clutch members. With the parts disposed as explained, the forearm can be raised on the elbow pivot or by the forward swinging of the full arm, without imposing any pull from the harness through the cord 58, and hence without aflectlng the position of the wrist. It is also apparent that by applying tensional strain by a pull from the harness upon the cord 58, the forearm can be raised, but in this case, the frictional pressure of the cord on the pulley or spool clutch member 85, will cause the .clutch mechanism and the wrist to turn the hand with the palm away from the operator's face for about one-third of a full hand turning movement, this backward turning continuing until the said cord in the upward movement of the arm has attained the common plane of pivots 5 and 5|. The length of cord 58 between pivot 5 and the top of the sheave 59 is less at this time than before the sheave attains such plane, and diminishes as the arm continues its upward movement, and as the sheave passes-above the plane mentioned, the cord reverses the turning movement of. the clutch mechanism to bring the palm of the hand toward the operator's face. The desirability of this back and forth hand turning movement will be apparent, especially when one is at table or desk with the forearm in an intermediate or partly raised position, as at such time if the cord runs in a straight line between pivots 5 and 5|, and the top of the sheave 59, the hand has been turned backward to its extreme limit, and ready to be turned forward as the forearm is raised to cause the hand to approach the face and dispose a fork, for instance for conveying food to the mouth. Upon lowering the forearm the turning movements described are reversed. As the forearm cannot operate under the application of tensile strain applied from the harness to cord 58, without concurrent wrist rotation, it is essential, to avoid turning the hand past the desired position with the palm facing and adjacent the mouth, to'utilize only part of the forearm movement in effecting turning of the hand.

To make clear the action of each part in accomplishing the results set forth, it will be noted that with the clutch held engaged by spring 42 and the dog 52 holding the lever against action by spring 44, the arm 45 against the frame 49a, and the pin 49 withdrawn, the tensionable pull on cord 58 turns the clutch members to effect backward turning of the hand. Continued movement reverses the turning of the clutch mechanism to effect the turning of the hand to dispose the palm facing the mouth as the upward movement of the forearm ends, these actions reversing as the forearm is brought back to alignment with the upper arm.

To look the wrist against turning, the cord 55 is caused by a pull of the harness, to trip the dog 52, and permit the spring 44, to overcome spring 42, and advance pin 49 and withdraw the clutch member 48 from engagement with clutch member 85. This leaves clutch member 48 free to revolve without affecting the locked wrist so that the forearm can be raised or lowered with the cord 58 slipping on the spool or clutch member. If the cord 58 is tensioned to apply pressure on the pulley or spool member 40 and turns the same, one of its ears 4| strikes lever arm 45 and rocks the lever against the resistance of spring 44 until the lever arm abuts frame arm 49a, and hence withdraws pin 49 and permits 42 to advanee clutch member 40 and the dog 62 to drop back of the lever and thereby prevent spring 44 from effecting declutching operation. In the advance of the clutch 40, an ear ll snaps into notch 31, so that as the arm moves upwardly both clutch members rotate and turn the hand backwardly, and then as the change of pull of the cord 58 reverses the turning of the clutch members, the hand is correspondingly turned. If at any time the ears and notches are not aligned from any cause for instant engagement when the spring 44 is restrained and spring 42 is free to advance member 40, the rotary movement of the latter immediately realigns its ears II with the notches 31, of the, at this time, stationary pulley or spool member. I

From the foregoing and the drawings, it will be apparent that I have produced an artificial arm for above elbow amputations which embodies the features of construction and operation set forth as desirable, and it is to be understood that while I have described and illustrated the preferred construction, I reserve the right to all changes within the spirit of the invention and without the ambit of the prior art.

I claim:

1. An artificial arm including an upper arm, a forearm pivoted to the upper arm, and a handcarrying wrist, a circular frame rigid with and within the forearm and rotatably connected to the wrist and provided with a closing section and a cylindrical axial stem projecting into the wrist, a clutch member journaled on the stem and abutting the closing section and provided with an outwardly projecting wall having a peripheral notch and an external flange concentrically surrounding and spaced from said stem, means engaging the said stem and the clutch member to hold the latter against sliding away from said closing section, a disk secured on the clutch member flange and in rigid relation to the wrist, a clutch pulley rotatably and slidingly mounted on the first-named clutch member and provided with a peripheral lug, a spring to urge the clutch pulley to interlock with the first-named clutch member by causing the lug of one to engage the notch of the other when in alignment, a rock lever on the closing section and in engagement with the slidable clutch member, a spring tending to cause the lever to unclutch the clutch members, and a dog for preventing unclutching operation.

2. An artificial arm including an upper arm, a forearm pivoted to the upper arm, a hand-carrying wrist, a circular frame rigid with and within the forearm and rotatably connected to the wrist and provided with a closing section and a cylindrical axial stem projecting into the wrist, a clutch member journaled on the tubular stem and abutting the closing section and provided with an outwardly-projecting wall having a peripheral notch and an external flange concentrically surrounding and spaced from said stem, means engaging the said stem and the clutch member to hold the latter against sliding away from said closing section, a disk secured on the clutch member flange and in rigid relation to the wrist, a clutch pulley rotatably and slidably mounted on the first-named clutch member and provided with a peripheral lug, a spring to urge the clutch pulley to interlock with the firstnamed clutch member by causing the lug of one to engage the notch of the other when in alignment, a rock lever on the closing section and in engagement with the slidable clutch member, a

spring tending to cause the lever to unclutch the clutch member, a dog for preventing unclutching operation, and a pull cord engaging the clutch pulley and adapted to slip thereon to avoid rotation of the wrist when the forearm is raised by centrifugal force or by lifting without strain applied to the cord,.but when tensional strain is applied to the cord, will turn the interlocked clutch members and the wrist.

3. An artificial arm including an upper arm, a forearm pivoted to the upper arm, and a handcarrying wrist, a circular frame rigid with and within the forearm and rotatably connected to the wrist and provided with a closing section and a cylindrical axial stem projecting into the wrist, a clutch member journaled on the tubular stem and abutting the closing section and provided with an outwardly-projecting wall having a peripheral notch and an external flange concentrically surrounding and spaced from said stem, means engaging the said stem and the clutch member to hold the latter against sliding away from said closing section, a disk secured on the clutch member flange and in rigid relation to the wrist, a clutch pulley rotatably and slidingly mounted on the first-named clutch member and provided with a peripheral lug, a spring to urge the clutch pulley to interlock with the firstnamed clutch member by causing the lug of one to engage the notch of the other when in alignment, a rock lever on the closing section and in engagement with the slidable clutch member, a spring tending to cause the lever to unclutch the clutch members, a dog for preventing unclutching operation, and a pull cord engaging the clutch pulley and adapted to slip thereon to avoid rotation of the wrist when the forearm is raised by centrifugal force or by lifting without strain applied by the cord, but which when tensional strain is applied by the cord, will turn the interlocking clutch members and the wrist, one end of said cord being anchored to the upper arm eccentrically of the pivot and the other end susceptible for operation when subjected to an upward pull, to exert tensional force to impart an oscillatory movement to the clutch mechanism and the wrist and hand.

4. An artificial arm comprising an upper arm, a forearm pivoted to the upper arm, and a handcarrying wrist, the hand having pivoted fingers, a rock-shaft within the hand for effecting closing and opening movements of the fingers, a worm gear segment projecting from the rock shaft, a worm wheel enmeshed with the worm gear to impart rotary movement thereto, and

' provided with drum trunnions, a shaft paralleling the axis of the worm wheel, a peripherally grooved segment on said shaft, a lever rotatable with the segment, a retractile spring connecting the lever with a fixed part-of the hand, and a pull cord extending through the arm and wrist member and into the hand and engaging the trunnions of the worm wheel and extending diagonally through and rigidly secured to the latter, and also engaging the groove of and permanently fastened to the segment, and adapted under a pull to turn the worm wheel and segment to open the fingers against the opposition of said spring.

5. An artificial arm, including a hand comprising a palm member, finger members hingedly connected to said palm, a crank shaft journaled in the palm member, levers connecting the fingers to the crank shaft, a toothed segment fixed on the crank shaft, a worm shaft journaled rotating the worm shaft and winding drum to open the fingers, a lever arm fixed to turn with the winding drum, and a retractilespring having one end attached to the palm and its other end to the lever to resist manual pull on the cord and to return the winding drum and worm segment to .close the fingers.

WILLIAM T. CARNES. 

